1. Field
The following description relates to a hybrid optical coupling module and a manufacturing method thereof, and more particularly, to a hybrid optical coupling module in which an optical unit for transmitting light and an electrical unit for converting an optical signal into an electrical signal are separately manufactured and then coupled in order to efficiently optically couple the optical unit and the electrical unit, and a manufacturing method thereof.
2. Description of the Related Art
With generalization of mobile devices including smartphones, smart pads, and the like, Internet traffic has continuously increased, and routers, switches, transmission devices, and the like with a high speed and large capacity have been realized so as to efficiently transmit the Internet traffic.
In order to increase the transmission capacity per unit time, a method in which optical signals with different wavelengths are subjected to wavelength division multiplexing (WDM) and transmitted to a single optical fiber in a backbone transmission network has been mainly used since 2000, and even in case of an access network, technologies in which optical signals with different wavelengths are bidirectionally transmitted to a single optical fiber have been commercialized. Even in an Ethernet field, a WDM method or a method in which parallel transmission is performed through a ribbon fiber has been likewise standardized.
In case of 40G Ethernet, a 10G×4 channel coarse wavelength division multiplexing (CWDM) method has been employed as a standard in order to transmit a single mode fiber of 10 km, and in case of 100G Ethernet, a 25G×4 channel local area network (LAN)-WDM method has been employed as a standard in order to transmit single mode fibers of 10 km and 40 km.
An optical transceiver denotes a module that performs optical transmission and reception functions in an optical communication device such as an optical transmission system, a large-capacity router, a switch, or the like which uses an optical fiber as a medium.
In such an optical transceiver module, a structure in which an optical component for performing optical-electric conversion and electric-optical conversion functions is provided and a plurality of optical signals can be simultaneously connected so as to receive signals of a large capacity has been proposed. As an example, in the WDM method, a method of using a planar lightwave circuit (PLC) has been mainly used in order to multiplex (MUX) or demultiplex (DMUX) signals with several wavelengths. In case of a double PLC, arrayed waveguide grating (AWG) may be used or various grating technologies may be used in a silica or silicon-based process.
Since a PLC device is a passive component, a complete product such as an optical receiver module may be obtained only when the PLC device should be coupled with an active component such as a photo diode (PD). Here, the components are made of different materials, and therefore there are difficulties in simultaneously manufacturing the components on a single substrate in the same processing.
Accordingly, the PLC, a light-emitting device (LD: laser diode), and a light-receiving device (PD: photo diode) which have been respectively manufactured in an individual processing should be coupled with each other, which is called hybrid integration.
As a method of coupling the PLC and the PD, a butt coupling method of directly coupling light emitted from a core of the PLC or a method of coupling light by reflecting a path of light at an angle of 90° using a mirror surface 1 with an angle of 45° as shown in FIG. 1 is widely used.
An existing 90° reflection coupling method has a structure in which a PD is mounted on a PLC 2 or a mounting board 3 is put on the PLC 2, and the PD and a transimpedance amplifier (TIA) are sequentially disposed, and therefore there are disadvantages in that a corresponding test may be performed only after all components 4 are assembled and the components should be thrown out in their entirety when a defect occurs, resulting in degradation in mass-productivity. In particular, a defect is more likely to occur when a large number of channels are used, and the components should be thrown out in their entirety when even only one channel improperly operates.
In addition, an active area of a PD that detects light becomes smaller at a higher speed, and therefore coupling efficiency is degraded as a distance between a reflection surface 1 of the PLC 2 and the active area of the PD becomes longer.